We will conduct a randomized, placebo-controlled clinical trial of the effectiveness of conjugated equine estrogens (CEE) in retarding bone loss from the proximal femur in women aged 65 years or older and who have not sustained any osteoporotic fractures. In this trial we will also test the subgroup hypotheses that the effectiveness of CEE in this regard is a function of the rate of bone remodelling at the time therapy is initiated, and/or the rate of bone loss during the two years prior to therapy. The unique feature of this trial is that all participants will have completed two years of a non-intervention study (NIH AR39657) during which serial measurements of bone mass and biochemical markers of bone remodelling were recorded. That study is testing the hypothesis that the rate of bone loss, in women who are ten years or more postmenopause, can be predicted from the rate of bone remodelling, as has been demonstrated for women in the immediate postmenopausal years. If the hypotheses in these two consecutive studies can be proven to be correct we will have provided a means of identifying those older women at greatest risk for ongoing bone loss at an accelerated rate and therefore, most likely to derive greatest benefit from CEE therapy. We will also have provided a model for studying effectiveness of other potential strategies for minimizing bone loss from the proximal femur in women in this age group. Without losing the primary focus of our clinical trial (preservation of bone mass in the proximal femur in older women), we will also evaluate several secondary outcomes of the proposed clinical trial. We will evaluate the effect of CEE on bone mass in the lumbar spine and the forearm, and on stature. We will also examine the effect of CEE on libido and other aspects of quality of life in this age group.